Circuit interrupter with interlock means and terminal cover



Feb. 6, 1968 J. N. GROVES CIRCUIT INTERRUPTER WITH INTERLOCK MEANS ANDTERMINAL COVER 2 Sheets-Sheet 1 Filed Sept. 14, 1966 FIG. I.

FIGB.

INVENTOR John N. Groves WQTNESSES @XM BY awzm 4 M ATTORNEY Feb. 6, 1968J. N. GROVES CIRCUIT INTERRUPTER WITH INTERLOCK MEANS AND TERMINAL COVER2 Shet s-Sheet 2 Filed Sept.- 14, 1966 FIGA.

/lll FIG.2.

United States Patent CIRCUIT INTERRUPTER WITH INTERLOCK MEANS ANDTERMINAL COVER John N. Groves, Beaver, Pa., assignor to WestinghouseElectric Corporation, Pittsburgh, Pa., a corporation of PennsylvaniaFiled Sept. 14, 1966, Ser. No. 579,426

13 Claims. (Cl. 200168) ABSTRACT OF THE DISCLGSURE An improved circuitinterrupter comprises an insulating cover member movable from a positioncovering certain terminals to a position exposing the terminals forconnection, inspection and adjustment. Interlock means is provided toprevent closing of the interrupter when the terminals are uncovered andto prevent uncovering of the terminals when the interrupter is closed.The terminals are positioned such that they are accessible foradjustment from the front of the interrupter when the cover ispositioned to expose the terminals. An improved circuit interruptercomprises an insulating cover member movable from a position coveringcertain terminals to a position exposing the terminals for connection,inspection and adjustment. Interlock means is provided to preventclosing of the interrupter when the terminals are uncovered and toprevent uncovering of the terminals when the interrupter is closed. Theterminals are positioned such that they are accessible for adjustmentfrom the front of the interrupter when the cover is positioned to exposethe terminals.

For certain applications of circuit interrupters, it is desirable, inorder to reduce the possibility of accidental contact with liveterminals, to cover the terminals with an insulatnig cover that may bemovable to an uncovering position to permit wiring of the terminals andto permit inspection and adjustment of the terminals. For safetyreasons, it is desirable to provide that the circuit breaker will not bein the closed position when the terminals are uncovered.

Thus, an object of this invention is to provide an improved circuitinterrupter comprising an insulating cover that is movable from a firstposition covering certain terminals to a second position uncovering theterminals, which circuit interrupter comprises improved means forpreventing operation of the circuit interrupter to the closed positionwhen the terminals are uncovered.

Another object of this invention is to provide an improved circuitinterrupter comprising an insulating cover that is movable from a firstposition covering certain terminals to a second position uncovering theterminals with improved means preventing movement of the insulatingcover to the second position when the circuit interrupter is in theclosed position and for preventing operation of the circuit interrupterto the closed position when the insulating cover is in the secondposition.

A further object of this invention is to provide an improved circuitinterrupter comprising terminals that are spaced from front to back inthe interrupter with an insulating cover member that is positioned atthe front of the interrupter and movable from a position covering theterminals to a position uncovering the terminals, which terminals arealso spaced in a direction generally normal to the direction from frontto back of the circuit interrupter so that a worker can readily connectwires to the terminals and adjust the terminals from the front of thecircuit interrupter with a tool such, for example, as a screwdriver whenthe insulating cover member is in the uncovering position.

Patented Feb. 6, 1968 This invention is particularly advantageous in theart of enclosed circuit interrupters wherein workers must, on occasion,have access to the inside of the enclosure to wire the interrupters andto adjust the connections. This invention is particularly effective inthis art because the worker generally has access only through the frontof the enclosure and the terminals, which are safely covered from thefront, are readily exposed for wiring, adjustment and inspection fromthe front when the worker moves the terminal cover to an uncoveringposition. The interrupter may be enclosed in a sheet metal enclosure inthe manner disclosed in the patent to Pierce et al. No. 2,265,004 issuedDec. 21, 1941 and assigned to the assignee of the instant case.

A more general object of this invention is to provide an improvedrelatively inexpensive and compactly constructed circuit interrupter.

The invention, both as to construction and operation, together withadditional objects and advantages thereof, will be best understood fromthe following detailed description when read in conjunction with theaccompanying drawings.

'In said drawings:

FIGURE 1 is a top plan view, with parts broken away, of a circuitinterrupter constructed in accordance with principles of this invention,which interrupter is shown with the insulating cover member in theuncovering position;

BIG. 2 is a side elevational view of the circuit interrupter of FIG. 1with the insulating cover member being shown in the covering position infull lines and in the uncovering position in broken lines;

FIG. 3 is a side elevational view, with parts broken away generallyalong the line III-III of FIG. 1, of the circuit interrupter of FIG. 1;and

FIG. 4 is a sectional view taken generally along the line lV-IV of FIG.1 with part of the operating member being shown in broken lines in theclosed position.

Referring to the drawings, there is disclosed therein a three-polecircuit interrupter 3 comprising a metallic supporting plate 5. Thesupporting plate 5 (FIG. 3) comprises a flat front part at one end 7thereof for supporting an insulating contact and terminal enclosure 9.Two side plate portions 11 (only one of which is seen in FIG. 4) areformed integral with the supporting plate 5 in proximity to the otherend of the supporting plate 5 to provide a generally U-shaped supportpart for supporting an operating mechanism 13.

The operating mechanism 13 comprises a trip member 15 that is pivotallysupported between the side walls 11 on a pivot pin 17. The trip member15 is latched at the other end 19 thereof by means of a latch member 21that is pivotally supported intermediate the ends thereof on a pivot pin23 that is supported between the side walls 11. The latch member 21comprises a bentover latch part 24- at the lower end thereof that islatched by means of a latch member 25 that is pivotally supported on apivot pin 27. The part 24 of the latch 21 rests on a roller 26 at oneend of the latch 25. A lower part 28 of the latch 21 serves as a stop toprevent movement of the latch part 24 off of the roller 26 under normalcurrent conditions. The latch member 25 is biased in a clockwisedirection about the pin 27 to the latching position by means of acompression spring 29. A toggle link 37 is pivotally connected to thetrip member 15 at one end thereof by means of a pivot pin 39. A U-shapeddrive member 41, that comprises a pair of side plate parts connected bya bight part 42, is provided with a pair of slots 43 in the side plateparts at one end thereof. A pin 45, that is connected to the lower endof the link 37, fits in the slots 43 to operatively connect the drivemember 41 with the link 37. An

over-center tension spring 47 is connected at the lower end thereof tothe pin 45 and at the upper end thereof to a pin 49 that is connected tothe bight portion 51 of an inverted generally U-shaped operating member53. The inverted generally U-shaped operator member 53 is provided withnotches at the inner ends of the legs thereof that engage support pins55, that are supported on the side plates 11, to supoprt the operatingmember 53 for pivotal movement about the support pins 55. A hearingsupport 63, that is supported between the side plates 11, is positionedin parallel slots or tracks 65 in the side plate parts of the drivemember 41 to support the drive member 41 and to guide the drive member41 for generally rectilinear back-and-forth horizontal (FIG. 4)movement. An insulating contact carrier 67, that extends across allthree poles of the interrupter, is fixedly secured to the right end(FIG. 4) of the drive member 41. The contact carrier 67 is a moldedinsulating member having a separate window opening 69 therein at each ofthe three pole units of the circuit interrupter. A separate elongatedmovable bridging conducting member 71, having a pair of movable contacts73 at the opposite ends thereof, is supported hr each of the windowopenings 69 on the contact carrier 67. A spring member 75 is disposed ineach of the openings 69 to bias the associated bridging contact member71 to the right in the associated opening 69 to the position seen inFIG. 4, which movement is limited by the engagement of the bridgingcontact member 71 with part of the insulating contact carrier 67. As canbe seen in FIG. 1, wherein the front of the circuit interrupter is shownin plan view, the contact carrier 67 supports three bridging contactmembers 71 for the three pole units of the circuit interrupter. As canbe seen in FIGS. 1, 3 and 4, on each of the bridging contact members 71the two contacts 73are spaced in a direction from front to back in thecircuit interrupter.

The insulating enclosure 9 comprises a molded insulating base or supportmember 81, that is fixedly secured to the front side of the generallyplanar part 7 of the metallic support 5, and a molded insulating covermember 83. As is best seen in FIG. 1, the insulating base member 81 isprovided with a pair of opposite insulating side walls 85 and a pair ofspaced insulating barrier parts 87 which serve to divide the enclosurebase member into three adjacent compartment areas for the three poleunits of the circuit interrupter. The internal part of the base member81 is provided with molded insulating support means 89 (FIGS. 1 and 4)comprising a front insulating support 91 and a back insulating support93. The parts 85, 87, 91 and 93 are molded together as an integral unitas part of the base member 81. The cover member 83 is provided with twospaced elongated slots 101 (FIGS. 1 and 3) over the insulating barrierparts 87 of the base member 81. Two screws 103 pass through the slots101 and are threaded into tapped openings in the barriers 87 to securethe cover 83 to the base 81.

In each pole unit, an inverted generally U-shaped front conducting strip105 is positioned over the front of the support part 91 and secured inplace by means of a screw 107 that passes through an opening in theconducting strip 105 and that is threaded into a tapped opening in aplate 109 that is positioned in the cavity below the support part 91. Astationary contact 111 is supported on one of the legs of each of thestationary conducting strips 105. In each of the pole units, an invertedgenerally U-shaped conductor 115 is straddled over part of theassociated conducting strip 105, and a connecting screw 117 is passedthrough an opening in the conductor 115 and threaded into the conductor105. When it is desired to connect the conductor 105 in an electriccircuit, a wire is passed under the conductor 115 and the terminal screw117 is screwed down to provide a pressure type connection between theconducting wire and the conductor 105.

In each pole unit, a conducting strip 121 is supported on the associatedinsulating back support 93 and fixed on the back support 93 by means ofa terminal screw 123 that passes through an opening in the conductor 121and that is threaded into a tapped opening in a lower support plate 125.An upstanding tab portion 127 of the conductor 121 engages part of theinsulating support 89 to provide additional support for the conductor121. A stationary contact 129 is supported on each of the conductingstrips 121.

As can be seen in FIGS. 1 and 3, two overload relays 131 are mounted onopposite sides of the operating mechanism 13 and secured to the sideplates 11 by means of a plurality of screw members 133. The overloadrelays 131 are well known types of relays comprising a bimetal snap diskthat when heated a predetermined amount snaps inward toward theoperating mechanism. The relays are constructed, and they operate, inthe same general manner as that disclosed in the above-mentioned patentto Pierce et al., No. 2,265,004. Thus, the construction and operation ofthe relays are set forth only briefly in this case. As can be seen inFIG. 1, a pair of spaced conductors 135 and 137 are supported at thefront of each relay. In each of the relays a suitable heating conductoris connected to bridge the associated conductors 135, 137 and to heatthe bimetal disk of the relay in response to current flow through therelay. A terminal screw 139 (FIG. 3) is connected to each of theconductors 135, and a terminal connecting screw 141 is connected to oneend of each of the conductors 137. As illustrated in FIGS. 1 and 3, inthe two outer poles of the three pole interrupter an insulated conductor145 is connected at one end to the stationary conducting strip 121 bymeans of a terminal screw 123 and at the other end to the conductor 135of the associated overload relay 131 by means of a terminal screw 139.There are only two relays used in the illustrated three-poleinterrupter. In the center pole of the three-pole circuit interrupter,an insulated conductor 151 is connected at one end thereof to theassociated conducting strip 121 by means of the terminal screw 123, andat the other end thereof to a conducting tubular member 153 (FIG. 4)that is provided with a tapped opening therein for receiving a terminalscrew 155.

The circuit through the center pole unit (FIG. 4) extends from aconducting line that would be connected to the conductor 153 by means ofthe terminal screw 155, through the conductor 153, the conductor 151,the conductor 121, the stationary contact 129, the movable contact 73,the bridging conductor 71, the stationary contact 111, the conductor 105to a conducting line that would be connected to the conductor 105 bymeans of the terminal screw 117. The circuit through each of the outerpole units (FIGS. 1 and 3) extends from a conducting line that would beconnected to the conductor 137 by means of the terminal screw 141through the conductor 137, the heating conductor (not shown) of theoverload relay, the conductor 135, the conductor 145, and then throughthe associated terminal strips and contact structures that are identicalto those disclosed in FIG. 4, to a conducting line that would beconnected to the associated conducting strip 105 by means of theassociated terminal screw 117.

An insulating handle structure 159, comprising an insulating handle part161 and an arcuate shield part 163, is fixedly secured to the bightportion of the operating lever 53 by means of the pin 49 (FIG. 4). Thecircuit interrupter 3 is of the type that is used at many installationsin an enclosure of the type having an openable cover and an opening inthe cover that receives the handle part 161 of the handle structure 159for external manual operation. This type of structure is disclosed inthe above-mentioned patent to Pierce et al No. 2,265,004. The arcuateshield 163 serves to close the opening in the outer enclosure cover inall positions of the handle structure 159.

The circuit interrupter 3 is shown in the olf or open position in FIG.4. When it is desired to close the circuit interrupter, the handlestructure 159 is mainly operated to move the operating member 53 aboutthe pivot 55 in a clockwise (FIG. 4) direction from the off or openposition to the on or closed position. During this movement, the line ofaction of the overcenter tension spring 47 is moved to the right of theline between the pins 45, 39 whereupon the spring 47 serves to snap thetoggle link 37 in a counterclockwise direction about the pin 39. Duringthis movement, the pin 45 at the lower end of the link 37 moves to theright moving in the slot 43 in the drive member 41 to move the drivemember 41 to the right. This movement is a generally rectilinearmovement with the drive member 41 being guided by means of the pin 63that fits in the tracks 65. Movement of the drive member 41 to the rightmoves the insulating contact carrier 67 to the right to thereby move allthree of the bridging contact members 71 from the open position seen inFIG. 4 to a closed position wherein each pair of movable contacts 73engage the associated stationary contacts 111, 129. Contact pressure ismaintained by means of the springs 75 that permit the contact carrier 67to move to the right a short distance after the movable contacts 73 haveengaged the stationary contacts 111, 129. Reverse movement of the handlestructure 159 from the closed position to the open position moves theline of action of the over-center tension spring 47 to the left of theline between the pins 45, 39 to thereby move the toggle 37 clockwiseabout the pin 39 which movement drives the drive member 41 to the leftto move the insulating carrier 67 to the left to thereby move thebridging contact members 71 back to the open position as seen in FIG. 4.The insulating contact carrier 67 and bridging contact members 71 moveback and forth in a direction generally normal to the direction fromfront to back, which front to back direction is the direction of spacingof the stationary contacts 111, 129 and the direction of spacing of themovable contacts 73.

When the circuit interrupter is in the closed position and an overloadappears in one of the poles, one of the heaters in one of the relays 131becomes heated sufliciently to actuate the associated bimetal whereuponthe associated bimetal snaps to move a cam member 164 inwardly throughan opening in the associated supporting plate 11 to thereby cam thelatch 25 in a counterclockwise direction about the pivot 27 to releasethe latch 21 permitting the latch 21 to move in a counterclockwisedirection about the pin 23 to thereby release the trip member 15. Thereleased trip member 15 pivots in a clockwise direction about the pivot17 under the force of the spring 47. During this movement the line ofaction of the spring 47 becomes positioned on the left of a line betweenthe pins 45, 39, and the link 37 is moved in a clockwise direction aboutthe pin 39. During this movement the pin 45 moves to the left and upwardin the slots 43 coming against the edges of the slots 43 to drive thedrive member 41 to the left to move the three bridging contact members71 to the left to a tripped open position. During the tripping operationthe handle structure 159 is stopped in a tripped position intermediatethe on and off positions in a well known manner. The circuit interrupteris reset after a tripping operation by movement of the handle structure159 to the complete off position. During this move-ment, a part 167 onthe operating iever 53 engages the trip member 15 to pivot the tripmember 15 in a counterclockwise direction about the pivot 17 moving thelink member 37 and trip member 15 back to the position seen in FIG. 4.During this movement the latch member 21 is forced back into thelatching position by the end 19 of the trip member 15. The spring 29again biases the latch 25 and latch 21 into the latching position seenin FIG. 4 so that upon release of the handle structure 159 the parts arereset in the position seen in FIG. 4. Thereafter, the circuit breakercan be operated in the same manner hereinbefore described.

If it is desired to wire the terminals 123, 117 or to inspect or adjustthe connection at the terminals 123, 117, a worker can loosen the screws103 (FIGS. 1-4) and slide the insulating cover 83 from the coveringposition seen in FIG. 4 to the uncovering position seen in FIGS. 1 and3. As will be understood with reference to FIGS. 1 and 2, the cover 83comprises generally planar track parts 181 at the opposite sides thereofand lower generally planar track parts 183 at the opposite sides thereofwhich planar parts 181, 193 rest and slide on planar parts and 187 onopposite sides of the insulating enclosure part 81. Thus, the covermember 83 is slidable along the surfaces 185, 187 back to the uncoveringposition seen in FIGS. 1 and 3. During this movement, the screws 103engage in the slots 101 (FIGS. 1 and 3) to guide the cover member 83 forgenerally rectilinear movement back to the uncovering position. With thecover 83 in the uncovering position seen in FIG. 3, a worker has accessto the terminal screws 117, 123 (FIG. 1) from the front of the circuitinterrupter and the worker can use an elongated screwdriver type toolextending inward normal to the plane of the paper as seen in FIG. 1 andnormal to the front of the circuit interrupter to work the screws 117and 123 to adjust or connect the terminal connections. It can be seenthat in FIG. 1 a worker can visually inspect the connections at theterminals when the cover 83 is in the uncovering position seen in FIGS.1 and 3. The circuit interrupter is in the open or off position in FIG.1 and 3, and it can be seen that the part 189 of the insulating cover"83 is positioned under the part 163 of the operating handle structure159 so that if an attempt is made to close the circuit interrupter whenthe cover 83 is in the retracted or uncovering position the part 163 ofthe handle structure 159 will engage the part 189 of the cover 83 toprevent movement of the handle structure 159 to the closed position tothereby prevent closing of the circuit interrupter when the cover 83 isin the retracted or uncovering position. After the terminals 117, 123have been wired, adjusted, or inspected, a worker can slide the cover 83back to the position seen in FIG. 4 and then tighten the two screws 103to thereby secure the cover 83 in the covering position. Thereafter, thehandle structure 159 can be freely moved between the closed and openpositions in the manner previously described. It can be understood thatthe screws 103 can be tightened to secure the cover in the secondposition if desired.

As can be seen in FIG. 4, when the insulating cover 83 is in thecovering position and when the handle structure 159 is in the closedposition (shown in broken lines in FIG. 4), the part 163 of the handlestructure 159 will engage the part 189 of the insulating cover 83 toprevent movement of the insulating cover 83 to the retracted oruncovering position. Thus, a worker must operate the circuit interrupterto the opening position to permit movement of the cover 83 from thecovering position seen in FIG. 4 to the uncovering or retracted positionseen in FIG. 3.

As can be seen in FIGS. 1-4, the contacts 73 are spaced from front toback and the contacts 111, 129 are spaced from front to back. Theterminals 117, 123 are spaced from front to back and also lengthwise inthe direction of movement of the bridging contact member '71 so thatboth rows of terminals 117 and 123 are accessible (FIG. 1) forinspection and for operation by means of a screwdriver type tool fromthe front of the circuit interrupter when the cover 83 is in theretracted or uncovering position seen in FIGS. 1 and 3.

It is also to be noted that if it is desired to inspect the contacts 73,111, 129, the cover 83 can be removed by removing the screws 183 andcompletely removing the cover member 83 whereupon a person can visuallyinspect the contacts from the front of the circuit interrupter.

From the foregoing, it can be understood that there is provided, by thisinvention, an improved circuit interrupter comprising an insulatingcover that covers certain terminals of the circuit interrupter in oneposition and that is movable to a retracted or uncovering position toexpose the terminals for wiring, adjustment and inspection from thefront of the interrupter. The circuit interrupter comprises aninsulating contact support part that supports the bridging stationarycontacts in two rows that are spaced from front to back and alsolengthwise in the direction of movement of the bridging contact memberwhereby the six terminals of the two rows are ex posed to a worker forfront inspection and accessible to the worker who can wire or adjust theterminals from the front of the interrupter with a screwdriver typetool. Two screw members extend through elongated slots in the insulatingcover to secure the cover to the front of the insulating support. Whenthe circuit interrupter is in the closed position, the operating handlestructure of the interrupter will engage the insulating cover to preventmovement of the insulating cover from the covering po sition to theretracted or uncovering position. When the circuit interrupter is in theopen position, a worker need only loosen the two securing screws andslide the cover back to the retracted or uncovering position to exposethe terminals. When the insulating cover is in the retracted oruncovering position, the insulating cover engages part of the operatinghandle structure to prevent accidental operation of the circuitinterrupter to the on or closed circuit position. When the exposedterminals have been wired, inspected or adjusted, the worker can thenmove the insulating cover back to the covering position and tighten thescrews to secure the parts in place. Thereafter, the circuit interruptercan be freely operated between the open and closed positions. When it isdesired to inspect the contacts, the screws can be completely removedand the insulating cover can then be removed whereupon the contacts areexposed for inspection from the front of the circuit interrupter.

While the invention has been disclosed in accordance with the provisionsof the patent statutes, it is to be understood that various changes inthe structural details and arrangement of parts may be made withoutdeparting from some of the essential features of the invention. It isdesired, therefore, that the language of the appended claims be given asreasonably broad an interpretation as is permitted by the prior art.

I claim as my invention:

1. A circuit interrupter having a front and a back, said circuitinterrupter comprising insulating support means, a stationary contactstructure supported on said insulating support means, a movable contactstructure movable recitlinearly between opened and closed positionsrelative to said stationary contact structure, terminal means on saidinsulating support means for connecting said stationary contacts in anelectric circuit, an operating mechanism comprising a manually operablehandle structure, said handle structure being manually operable from thefront of said circuit interrupter between an open position and a closedposition to operate said operating mechanism between an open and aclosed position to move said movable contact structure to open and closesaid contacts, an insulating cover on said insulating support means atthe front of said circuit interrupter in a first position covering saidterminal means, said insulating cover being movable on said insulatingsupport means from said first position to a second position uncoveringsaid terminal means, and said insulating cover in said second positioncooperating with said'operating mechanism to prevent operation of saidoperating mechanism to the closed position.

2. A circuit interrupter according to claim 1, said cover being movablefrom said first position to said second posi tion when said operatingmechanism is in the open position, and said operating mechanism in theclosed position thereof cooperating with said cover to prevent movementof said cover from said first position to said second position.

3. A circuit interrupter according to claim 1, securing means in asecuring position to secure said cover in said first position on saidinsulating support means, said securing means being loosenable to aposition to permit movement of said cover from said first position to asecond position on said insulating support means, and said securingmeans being workable to a securing position to secure said cover in saidsecond position on said insulating support means.

4. A circuit interrupter according to claim 1, said terminal means onsaid insulating support means being frontadjustable to effect anelectrical connection between said stationary contact structure and aconducting wire, securing means in a securing position securing saidinsulating cover against movement in said first position on saidinsulating support means, said securing means being adjustable to anon-securing position, said insulating cover being slidable on saidinsulating support means from said first position to said secondposition when said operating mechanism is in the open position and saidsecuring means is in said non-securing position, when said securingmeans is in said non-securing position and said operating mechanism isin the closed position said operating mechanism engaging said insulatingcover to prevent movement of said insulating cover from said firstposition to said second position, when said insulating cover is in saidsecond position on said insulating support means said front-adjustableterminal means being uncovered and accessible for front adjustment, andsaid insulating cover comprising stop means to engage said operatingmechanism to prevent movement of said operating mechanism to the closedposition when said insulating cover is in said second position.

5. A circuit interrupter according to claim 4, said insulating coverhaving a pair of parallel elongated slots therein, said securing meanscomprising a separate screw passing through each of said slots andthreaded into tapped means in said insulating support means, and saidscrews and said slots serving as guide means to guide said cover forrectilinear back and forth movement between said first and secondpositions when said screws are in the non-securing position thereof onsaid insulating support means.

6. A circuit interrupter according to claim 1, said handle structurecomprising a molded insulating handle member, and said insulating coverin said second position being in the path of movement of said moldedinsulating handle member to engage said handle member to preventoperation of said operating mechanism to the closed position.

7. A circuit interrupter according to claim 6, said cover being movablefrom said first position to said second position when said operatingmechanism is in the open position, and when said operating mechanism isin said closed position said handle member being in the path of movementof said cover to engage said cover to prevent movement of said coverfrom said first position to said second position.

8. A circuit interrupter according to claim 6, securing means in asecuring position to secure said cover in said first position on saidinsulating support means, said securing means being loosenable to aposition to permit movement of said cover from said first position tosaid second position on said insulating support means, and said securingmeans being workable to a securing position to secure said cover in saidsecond position on said insulating support means.

9. A circuit interrupter having a front and a back, said circuitinterrupter comprising insulating support means, a pair of stationaryconductors supported on said insulating support means in a spacedrelationship spaced in a direction from the front to the back of saidinterrupter, a separate stationary contact on each of said stationaryconducors, a terminal connector for each of said stationary conductors,each of said terminal connectors being workable to removably connect aconducting wire to the associated stationary conductor, a contactcarrier, a bridging contact structure on said contact carrier andcomprising a movable conductor and a pair of spaced movable contacts onsaid movable conductor spaced in the direction from the front to theback of said interrupter, an operating mechanism comprising a manuallyoperable handle structure manually operable from the front of saidcircuit interrupter between two operating positions to eifectback-and-forth movement of said movable contact carrier and saidbridging contact structure in a direction generally normal to thedirection from the front to the back of said interrupter to thereby movesaid movable contacts into and out of engagement with said stationarycontacts, an insulating cover member supported on said insulatingsupport means at the front of said circuit interrupter in a firstposition covering said terminal connectors from the front of saidinterrupter, said insulating cover member being movable to a secondposition wherein said terminal connectors are uncovered from the frontof said interrupter, said terminal connectors in addition to beingspaced in the direction from the front to the back of said interrupterbeing spaced in the direction of said movement of said movable contactcarrier and said bridging contact structure whereby when said insulatingcover member is in said second position said terminal connectors areboth accessible for adjustment from the front of said interrupter.

10. A circuit interrupter according to claim 9, each of said terminalconnectors comprising a terminal screw rotatable to effect an electricalconnection between the associated stationary conductor and a conductingwire, and when said insulaing cover member is in said second positionsaid terminal screws being accessible to be worked by means of ascrewdriver type tool that may be extended into said interrupter in thedirection from the front to the back of said interrupter.

11. A circuit interrupter according to claim 9, said insulating covermember having a pair of elongated slots therein, securing meanscomprising a pair of screws passing through said slots and being in asecuring position screwed into threaded means in said insulating supportmeans to secure said insulating cover member to said insulating supportin said first position, said screws being screwable in said threadedmeans to a non-securing position on said insulating support means, saidinsulating cover member being movable from said first position to saidsecond position when said screws are in said non-securing position, saidscrews and said slots cooperating when said screws are in saidnon-securing position to guide said insulating cover member forrectilinear sliding movement on said insulating support means betweensaid first and second positions.

12. A circuit interrupter according to claim 9, securing means in asecuring position to secure said insulating cover member againstmovement in said first position on said insulating support means, saidsecuring means being adjustable to a non-securing position to permitmovement of said insulating cover member on said insulating supportmeans, said handle structure engaging said insulating cover member toprevent movement of said insulating cover member from said firstposition to said second position when said securing means is in saidsecuring position and said handle structure is in the closed position,when said securing means is in said non-securing position and saidhandle structure is in the open position said insulating cover memberbeing movable from said first position to said second position, and whensaid insulating cover member is in said second position said insulatingcover member engaging said handle structure to prevent movement of saidhandle structure to said closed position.

13. A circuit interrupter according to claim 11, said handle structurein the closed position thereof engaging said insulating cover member toprevent movement of said insulating cover member from said firstposition to said second position, said handle structure in the openposition thereof being clear of said insulating cover member to permitmovement of said insulating cover member from said first position tosaid second position, and said insulating cover member in the secondposition thereof engaging said handle structure to prevent movement ofsaid handle structure to the closed position.

References Cited UNITED STATES PATENTS 4/1924 Platt 20050.1 7/1929 Sachs20050.1

